Abstracts 2005 - The Psychonomic Society

Saturday Afternoon Papers 221–227
tendency was slight for actual movement but more pronounced for
imagined movement. Thus, similar processes appear to operate during
actual and imagined action, but accuracy requirements are
weighted more heavily in imagination.
2:30–2:45 (221)
Moving Farther but Faster: An Exception to Fitts’s Law. JOS J.
ADAM & ROBIN MOL, University of Maastricht, JAY PRATT, University
of Toronto, & MARTIN H. FISCHER, University of Dundee
(read by Jay Pratt)—Fitts’s law holds that movement time (MT) increases
with higher indexes of difficulty (IDs; resulting from smaller
targets and/or longer movement distances) across a wide range of
movement tasks. Specifically, Fitts’s law states that MT increases as
a logarithmic function of ID. Here we report a series of studies that
show a violation of this law: When the target appears in a structured,
linear display with multiple placeholders indicating the possible target
locations, MTs to the most distant target (i.e., the highest ID) do
not fit the logarithmic function that describes the less distant targets.
Rather, the MT to the most distant target is equal to or less than the
MT to the second most distant target. These experiments suggest that
Fitts’s law may be limited to egocentric visuomotor action, and, moreover,
that the visual control of hand movements may use allocentric,
in addition to egocentric, spatial information.
2:50–3:05 (222)
Rhythm in Golf. RICHARD J. JAGACINSKI, TAE HOON KIM, &
STEVEN A. LAVENDER, Ohio State University—Golfers often talk
about the rhythm of a golf shot without offering a precise definition
of this term. The relative timing of the force pattern at the clubhead
versus the force pattern against the ground provides a simplified definition
of golfing rhythm. One advantage of this definition is that it
facilitates comparisons across individuals with markedly different
kinematic patterns of limb movement. Both (3 vs. 2) and (3 vs. 3)
rhythmic force patterns were commonly exhibited in a study of short golf
shots into a target net. Across individuals, shot accuracy was strongly
correlated with the timing of the final weight shift relative to the force
pattern early in the swing and also with the range of forces at the clubhead
prior to impact.
3:10–3:25 (223)
Action Simulation Mediates Synchronization in Piano Duet Playing.
BRUNO H. REPP, Rutgers University, Newark, and Haskins Laboratories,
GÜNTHER KNOBLICH, Rutgers University, Newark, & PETER
E. KELLER, University of Management and Finance, Warsaw, Poland—
Ensemble musicians play in synchrony despite expressively motivated
irregularities in timing. We hypothesized that synchrony is achieved
by each performer internally simulating the concurrent actions of
other ensemble members, relying initially on how they would perform
in their stead. Hence, musicians should be better at synchronizing
with recordings of their own earlier performances than with others’
recordings. We required pianists to record one part from each of several
piano duets and later to play the complementary part in synchrony
with their own or others’ recordings. The pianists were also asked to
identify their own recordings. The pianists were better at synchronizing
with their own than with others’ performances, and they were able
to recognize their own recordings. Furthermore, synchronization accuracy
and recognition were correlated: Pianists who were relatively
accurate at synchronizing with their own performances were also
good at recognizing them. Thus, action simulation may underlie both
synchronization and self-recognition.
3:30–3:45 (224)
Dyspraxia, Autism, and the Cerebellum: A Case Study. MORTON
ANN GERNSBACHER, University of Wisconsin, Madison, & THOMAS
A. ZEFFIRO & JOHN W. VANMETER, Georgetown University Medical
Center—We provide a case study of a young male (current age
9 years, 7 mos.) who presents with genius-level intellectual skills, severe
oral and limb dyspraxia, and autistic traits. The child’s oral dys-
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praxia is so severe that he struggles to produce vocal sounds and oral
movements. His spontaneous utterances are belabored, primarily vocalic,
and relatively unintelligible. The child’s limb dyspraxia is so severe
that despite his genius-level IQ, he is unable to accomplish simple
commands such as “touch your nose,” his imitation is profoundly
impaired, and his manual gesture inventory is extremely limited.
These difficulties in executing volitional movements contrast with his
excellent coordination in tasks involving balance. Structural brain
imaging revealed a striking loss of white matter density in the vermis
of the posterior cerebellum and its connections, paralleling postmortem
analyses of “minimally verbal” individuals with autism. Implications
for the speech, imitation, and gesture deficits sometimes associated
with autism will be discussed.
Problem Solving
Civic Ballroom, Saturday Afternoon, 1:30–3:10
Chaired by Stellan Ohlsson, University of Illinois, Chicago
1:30–1:45 (225)
Multiple Difficulties in Insight Problem Solving: The Necklace
Problem. TRINA C. KERSHAW, STELLAN OHLSSON, & STACIE
HARISSIS, University of Illinois, Chicago (read by Stellan Ohlsson)—
In previous work, we (Kershaw & Ohlsson, 2004) have suggested that
insight problems are difficult because multiple converging difficulties—
perceptual, knowledge, and process factors—conspire against the solution.
In the present work, we apply this multiple-convergent-factors
principle to the necklace problem. Participants solved versions of the
necklace problem that were designed to eliminate one or more difficulties.
Problem perception was manipulated by having participants
build the three-link chains that figure in the problem. Process load was
reduced by eliminating the prices assigned to problem steps in the
standard presentation. The results show that the elimination of multiple
difficulties led to higher solution rates than the elimination of a
single difficulty. The results also show that participants in the process
condition had higher solution rates and solved more quickly than participants
in the perceptual condition. Implications for insight problem
solving theories will be discussed.
1:50–2:05 (226)
The Influence of Incentives on Attention During Problem Solving.
MAREIKE WIETH, Albion College, & BRUCE D. BURNS, University
of Sydney (read by Bruce D. Burns)—Our previous research has
shown increases in problem solving performance and memory due to
incentives. Attention is essential in determining what information is
processed, encoded, and later retrieved (Broadbent, 1958). It was
therefore hypothesized that incentives increased performance because
they either expanded or shifted attentional resources. Participants performed
in either dual-task (tone monitoring while solving insight and
incremental problems) or single-task (problem solving only) conditions.
Results showed that incentives increased problem solving performance
in the single-task but not in the dual-task condition. These
findings indicate that incentives lead to an increase in performance by
shifting attentional resources to the rewarded task rather than by increasing
the pool of resources available for problem solving. In accord
with this finding, where incentives were effective, they appeared to
change the quality of processing. This methodology has the potential
to provide further insight into how incentives affect cognitive
processes.
2:10–2:25 (227)
Mental Comparisons With Complex Structures: Kin-Like Structures,
Complex Trees, and Item-Specific Processing. CLAUDE G.
CECH, University of Louisiana, Lafayette—In work presented previously,
I showed that distance and congruity effects occurred with comparisons
of relative age of individuals from learned family trees. Of
particular significance was the finding that comparisons of nonlineal
relatives took longer, consistent with a claim that people were sensi-